Heat the vegetable oil in a skillet over medium heat. Stir in the onion, potato, and bay leaf. Cook and stir until the onion is transparent, about 5 minutes. Add the Brussels sprouts, red pepper, and chicken broth. Cover and cook until vegetables are tender, about 10 minutes. Remove the bay leaf. Toss with black pepper, to taste. Garnish with green onions, and serve immediately.